H.264 remains the dominant force in online video, as the video codec now accounts for more than two-thirds of online video, according to a blog post by MeFeedia Thursday. Meanwhile, Google’s WebM format has yet to gain any significant traction after being released a year ago.

H.264's market share continues to widen over competing video formats, as it now accounts for nearly 70 percent of videos indexed by MeFeedia. That’s a huge increase in a very short amount of time, as just last May, when only about 25 percent of videos were available in the H.264 format. And while the percentage growth has slowed in recent quarters, it remains the dominant format for streaming video delivery.

The growth in H.264 encodes is being driven by the adoption of video on tablet devices like the iPad , as well as connected TVs, Blu-ray players and other broadband-enabled video devices. Due to hardware acceleration built into many existing connected device chipsets, H.264 is by far the dominant format for smart TVs and related products.

It’s also an acknowledgement of the strength of the iPad for mobile viewing. There are more than 200 million iOS devices on the market, including 25 million iPads, and H.264 video is the best way to reach those devices. According to MeFeedia, the iPad has the highest engagement among devices, with 40 percent more videos viewed per use than Android, iPhone and desktop users.

While H.264 continues to dominate, the latest numbers on Google’s open-source WebM video format show that it has yet to catch on with publishers. More than a year after its launch, WebM accounts for less than 2 percent of videos indexed, according to MeFeedia. While that is expected to grow — particularly as YouTube continues its process of transcoding all its videos into the WebM format — it’s still a pretty small number for a codec that boasts fairly broad browser adoption and growing support from consumer device manufacturers.

WebM is supported by Firefox, Opera and Google’s Chrome web browsers. In that latter case, in fact, WebM is the default video codec supported for HTML5 video playback, as Google removed support for H.264 in the latest version of Chrome. It’s also gained some hardware backing from consumer electronics manufacturers like Samsung, LG Electronics and Cisco, and has been available on Android devices since the release of Gingerbread.

Despite growing support, it may still take some time before WebM gains the type of hardware acceleration required for broad publisher usage. The good news for Google — and for WebM advocates — is that things can change quickly in the online video market. One need only look at the massive increase in H.264 adoption to see that.